I was told that what I was witnessing at a revival meeting was 'laughter of the spirit'.
What is this? Is this truly from the Holy Spirit? If I don't believe it is from the
Holy Spirit, am I blaspheming? I am confused and have been worried about this for
a long time.

First of all I would suggest to you to relax. I see no reason
for you to be concerned of blaspheming the Holy Spirit. An act of blaspheming of
the Holy Spirit is shown in Scripture. It was done during the time of Jesus’ ministry
by the religious leaders of the time. This act of blaspheming the Holy Spirit that
the Pharisees did in that day occurred because after actually watching Jesus cast
out a demon, they refused to believe it was through the work of the Holy Spirit.
They said it was from the devil. It wasn't their words that condemned them it, but
what was in their hearts. Just because you are told by man that something THEY think
is blasphemous doesn’t make it so. In fact more than likely what you are witnessing
is people caught up in the emotions of the event.

To
attempt to answer your questions about 'laughter of the spirit', we should test every
spirit to see if it is of God. First, lets look at some scriptural aspects of the
Holy Spirit. By doing this, we can test this concept of 'laughter of the spirit';

But
the fruit of the Spirit is love, joy, peace, patience, kindness, goodness, faithfulness,
gentleness and self-control. Gal. 1:22-23 Notice the words, peace,
patience, gentleness and self-control. From what you saw and heard that day at the
revival, you would have to ask yourself, do these things agree with scripture? It
doesn't sound like it does. There is no scripture that I am aware of that specifically
gives support for that kind of 'laughter of the Spirit'.

As far as your confusion
on these things, again it is because you, as I are learning, and that's ok. We need
to pray to God for these answers, and always remember;

For God is not the
author of confusion but of peace, as in all the churches of the saints. 1 Cor. 14:33